1. Field of the Invention
The present invention relates to a medical image display apparatus for displaying a medical image, and, more particularly, to a medical image display apparatus for displaying a medical image having a thickness in a visual axis direction.
2. Description of the Related Art
A medical image display apparatus displays a medical image of a patient based on volume data obtained by medical image generating apparatuses such as X-ray computed tomography (X-ray CT) apparatuses, magnetic resonance imaging (MRI) apparatuses, and the like. The volume data is generated by overlapping slice images, which are generated by a medical image generating apparatus, in a slice axis direction.
The medical image display apparatus has MPR (Multi Planar Reconstruction) functions. The MPR functions are functions for generating a new image (MPR image) by performing a calculation to the volume data obtained by the medical image generating apparatus, that is, to a slice image group in the slice axis direction according to various arbitrarily designated parameters such as a cross section, a thickness, and the like.
As one of the MPR functions, there is a function for providing a thickness range with a thickness in a visual axis direction and projecting a maximum value, a minimum value, or an average value in voxel values of respective pixels in the thickness range (maximum value projection/minimum value projection/averaging value display) so that all the slice images in the thickness range are displayed as a sheet of image (for example, Japanese Patent Publications No. 8-227449 and No. 2006-263078).
However, in the MPR function described above, it is necessary to refer to all the slice images in the thickness range and to calculate data of the maximum value, the minimum value or the average value in the voxel values of the respective pixels in the slice image group. Thus, according to the MPR function, there is a tendency that a processing time necessary to calculate the data is increased and a display speed is reduced. In particular, when images are continuously displayed while moving a cross sectional position, that is, the thickness range in the visual axis direction little by little, the processing time necessary to calculate the data is increased and the display speed is reduced.